The present invention relates to mixed esters formed from estradiol and zeranol on the one hand and a diacid on the other.
The significance of administering estradiol when rearing animals is already known, particularly through the action on the metabolism of calcium. However, this estradiol is rapidly degraded in the organism where it is free. Hence the interest of using it in the form of an ester whose hydrolysis is calculated in such a way that estradiol is only gradually released into the organism. Therefore the use of esters formed with alkanoic acids such as acetic, propionic and pyruvic acids (Leo, Belgian Pat. No. 646,319; Ciba, Swiss Pat. No. 380,118; Gyogyzeripari Kutato Intezet, Hungarian Pat. No. 150,957; Lakeside, Laboratory U.S. Pat. No. 2,623,886; Lovens Kemiske Fabrikved, U.S. Pat. No. 2,467,460; Organon Laboratories, U.S. Pat. No. 2,841,598; Dutch Pat. No. 81,258; and British Pat. Nos. 771,308 and 833,582; and Volovel Skii, Soviet Pat. No. 166,334) are recommended. Alkanoic esters with one or two halogens or a mercapto or dialkylamino group (Syntex Corporation, U.S. Pat. No. 3,275,623; Teikoku Japanese Pat. Nos. 4,967/60 and 21,179/61), benzoic esters (the above-cited Hungarian Pat. No. 150,957, Laboratoire Francais de Chimiotherapie, French Pat. No. 1,290,876 Merck A.G., British Pat. No. 1,022,422; Villax German Pat. No. 1,200,822) and phenylpropionic esters (Leo, German Pat. No. 1,123,666) are also recommended.
It is also known that zeranol has a rare anabolizing property for animals. This compound is trihydroxy-7,14,16-methyl-3-oxa-2-oxo-1-benzo-[c]-tetradecene-12a,16a of the following formula
Its preparation and properties are described in U.S. Pat. Nos. 3,239,345, 3,239,348 and 2,196,019 of Commercial Solvents Corporation and in the corresponding French Pat. Nos. 6018M, 6612M, 6899M, 7807M and 1,481,985. When using this compound it is also important to select the esters in such a way that the duration of its effectiveness is increased. However, few esters of this compound are known and those which are known are light alkanoates described in U.S. Pat. No. 3,239,356 and French Pat. Nos. 6018M, 6899M, 7807M and 1,481,495 of Commercial Solvents Corporation.
The applicants have now discovered mixed esters formed from estradiol and zeranol whose anabolizing properties have proved to be remarkable. These esters are prepared from dicarboxylic acids.